Grinding wheel dresser



Jan. 12 1943. J. SNEED GRINDING WHEEL DRESS-ER Filed May 12, 1941 3' Shets-Sheet 1 i I INVENTOR. BY J f Jan. 12,1943, J.SNEED. 2,308,317

GRINDINFT, WHEEL DRESS ER FiledW/Iay 12, 1941 s sheets-sheet 2 INVENTOR.

v WQJMM Jan. 12, 1943. j SNEED 2,308,317

GRIND'INGWHEEL DRES'S'ER I I Filed May 12, 1941 3 Sheets-Sheet 3' Patented Jan. 12, 1943 V i v 2,308,317

GRINDING WHEEL DRESSER John Sneed, Huntington Woods, Mich., assignor to William F. Da'lzen, Detroit, Mich.

Application May 12, 1941, Serial No. 393,021

9 Claims.

This invention relates to thread grinding machines, and more particularly to dressing mcha nisms for the rotatable abrasive grinding wheel of said thread grinding machines.

It is the object herein to provide a dressing mechanism in combination with a thread grinding machine, said mechanism being a universal form dressing mechanism adapted to produce various shaped surfaces in the peripheral edge of the grinding wheel for accurately grinding out various shapes of threads.

It is the object hereof to provide a dressing mechanism which is readily removable from the thread grinding machine and interchangeable with other types or" dressing mechanisms.

It is the further object hereof to provide means for slidably supporting the dressing mechanism upon the grinding wheel support of a thread grinding machine; and also to provision compensating means between said thread grinding machine, said support, and said dresser for raising and lowering the grinding wheel support with a proportional movement of the dresser with respect to said support.

It is the further object of this invention to provide in said dressing mechanism means for removably and adjustably supporting templets for governing the form and shape to be dressed in the peripheral edge of the grinding wheel.

It is .the further object of this invention to provide a pivotally supported templet follower bar to which is secured to a diamond for reproducing in the thread grinding wheel by said diamond, the shape of said templet.

It is the further object hereof to provide in a dressing mechanism, a longitudinally adjustable templet support whereby a plurality of pitches may be reproduced in the grinding wheel with a single templet.

It is the still further object hereof to provide in a dressing mechanism, a laterally adjustable templet support whereby a proportionately smaller templet may be used than is required for obtaining a reproduction in the peripheral edge of the grinding wheel.

Other objects will be seen in the various arrangements of parts and combinations thereof as will be hereinafter described in connection with the appended drawings, of which:

Figure 1 is a front elevational view of the Figure 4 is an elevational section on line 4 of Figure 3.

Figure 5 is an end elevational view of the dressing mechanism.

Figure 6 is a sectioned elevational View of a slightly different form of dresser.

thread grinding machine and the dresser mecha The above drawings illustrate merely preferable embodiments of the invention, it being expressly understood .that it is not intended that the invention be limited thereby.

In the drawings, the grinding wheel dresser is generally indicated at A with its housing H vertically and reciprocably mounted within the support l2 with friction minimiizng ball races l3 interposed therebetween. Support i2, is joined to the vertically movable grinding wheel support l4 and is adapted to move therewith.

Hand, wheel l5 operating through suitable gears and a threaded shaft supported by column l9, raises and lowers housing I4 and the abrasive grinding wheel It with respect to said column. The dresser A and its housing I l are also raised and lowered by hand wheel l5 operating through the movable wheel support I4.

Lever I] has a lug l8 on its end adapted to support the housing H of the dressing mechanism. Said housing while resting upon the end of lever I1 is longitudinally and reciprocably slidable within the vertical support l2. Said lever is centrally pivoted at point 20 to the movable housing l l thereby providing an adjustable support for the pivot point 20.

The other end of lever ll also has a lug 2| for adjustable engagement with respect to column H7 at point 22.

An adjustable relation is maintained between lever I7 and column It as ,the wheel supporting housing hi is downwardly fed, whereby the dresser is permitted to properly engage the speripheral surface of the grinding wheel It in operative dressing position.

' A compensating screw 23 is longitudinally disposed within the bracket member 24 secured to the colunm IS. A washer 25 is secured upon the end of screw 23 by a nut 26; and the end of lever ii is beneath said washer at point 22 whereby a retaining means is provided preventing rotation of said lever. The calibrated head 2"! is threadably and adjustably disposed on the lower end of the compensating screw 23 and thereby provides a manually operable adjusting means permitting longitudinal adjustment of said compensating screw 23 whereby the lever I1 is correspondingly adjusted as desired. 7

Housing l4 slides relatively to column l9 with a suitable dovetail connection; and is adjustable with respect thereto by operation of hand wheel I5.

From time to time the grinding Wheel I3 becomes worn requiring a dressing operation; or on the other hand it may be desired to vary the form of the cutting edge thereof for grinding a particular shape of thread.

For these purposes the wheel dresser A is employed having a housing I I vertically and reciprocably mounted within the support I2 as above described, in connection with the Figures 1, 2 and 3.

The above dressing mechanism is a universal form dresser adapted to obtain any desired shape of peripheral grinding edge on the grinding wheel I6 depending upon the particular form of thread desired.

By utilizing the support I2 as illustrated in Figures 1, 2 and 3 and the ball races or ways I3 it is seen that dresser A is easily removable and interchangeable with any other type of dresser if desired.

Referring to Figures 3, 4 and 5 the dresser housing II has secured thereto the laterally disposed guide table 28 for the slidable dovetail block 29 which is adapted for longitudinal reciprocable adjustment in a slot 30 in said guide table.

Block 29 is also slotted at 3i to provide a dovetail support for the transversely slidable templet support 32 to which is removably secured templet 33 by bolts 34.

Said templet is a pattern from which the dressing device is manually controlled and from which is governed the dressing action of a diamond 35 within a suitable mounting 36 for obtaininga peripheral edge on the grinding wheel I6 similar in form to the particular templet chosen. To obtain any particular thread shape or pitch it will be seen that a plurality of templets 33 may be available for removable attachment to the laterally movable support 32.

A follower bar 31 with handle 38, provided upon its lower surface with a wedge shaped edge 39 as better seen in Figure 5, is pivoted intermediate its ends within housing II by means of the ball pivot 49 with its shank 4| secured thereto. Ball pivot 43 substantially spherical in shape is supported in a suitable socket in housing H,

and is adapted for pivotal movement therein in a plurality of directions. Shank 4| joined to ball pivot 49 extends upwardly and is suitably joined to the follower bar near its outer end thereby providing a universal pivotal support therefor. By manipulating handle 38 of follower bar 31 it is seen that with the ball pivot as a center, said bar and the diamond 35 that it carries are adapted for pivotal movement in any be pivoted.

sponds exactly in shape to the movement of the lower edge of the follower bar 31 as it travels over the surface of the templet 33, thereby reproducing its shape in the grinding edge of said grinding wheel I6.

The end of bar 31 is joined to the arm 42, which forms a part thereof the outer end 44 of which is adapted to vertical reciprocation Within slot 43, in housing I I as seen in Fig. 3 whereby a pivotal guide is obtained for the end of the follower bar. Arm 42 is downwardly disposed 'from the end of bar 31 adjacent the point at which the shank member M of ball pivot 40 engages the same. The outer end of arm 42 has a pivotal member 44 thereon, with respect to which said arm 42 and the follower bar 31 may It will be noted however that the member 44 is disposed within the slot 43 within housing II as shown in Fig. '3, which prevents any relative movement of member 44 with respect. to member 31, except for vertical reciprocation within said slot. However it will be noted that the arm 42 is pivotally connected to member 44. Consequently arm 42 may pivot with respect to member 44, while the latter may merely reciprocably slide up and down within slot 43.

It will be noted as essential that the center line of the ball pivot 40 is displaced from the center line of the pivot point 44 of arm 42. By this provision the follower bar 31 is prevented from twisting to one side or the other unless the same is moved laterally. With these two pivot points offset with respect to each other it is seen that there is a tilting action to follower bar 31 whenever said bar is moved laterally by handle A diamond mounting 36 provisioned within the follower bar 31, is adjustably secured therein preferably by a set screw 45. Referring to Figure 4 it is seen that said diamond mounting 36 is adapted to engage the peripheral edge of the grinding Wheel I5, and is manipulated with respect thereto by the follower bar 31 so as to reproduce in said peripheral edge a shape corresponding to the shape of the particular templet 33 which is secured to bracket 32. With the two pivotal supports 40 and 44 for the follower bar 31 it is seen that a very definite control is given to the movement of said bar on lateral translation thereof. This becomes particularly important in assuring that the diamond engages the grinding wheel normally, i. e. at substantially right angles thereto, as it is translated over its outer edge, in accordance with the pitch defined by the templet used. For instance where the grinding wheel is sought to be dressed at a sharp angle as where the included angle defined by the edges of two adjacent threads is small, it is highly important that the diamond be presented normally to the surface of the grinding edge. This means that the diamond, as it progresses over the grinding surface of the grinding wheel, engages the latter only on one side thereof, and is much less apt to be chipped, or to cause chips respect to the fixed pivot point 46, it is seen that 7 to be made in the wheel itself.

In operation, with the edge 39 positioned at the central point of the templet, the follower bar is manually or mechanically moved laterally over the surface thereof, which in turn governs the direction of cutting edge of the diamond 35 in mounting 33. Throughout the dressing operation it is desirable that the diamond be' presented normally to the grinding wheel to correspond to the normal positioning of'the edge 39 of bar 31 with respect to the surface of the templet 33 as said bar is moved over the same. The reason for this is that non-cutting edges of the diamond are kept clear of the grinding wheel.

In going over the templet the bar 31 is moved laterally and by action of trunnion 42 said edge 39 is at all times presented normally to the templet surface.

For regulating laterally the resultant form of the peripheral edge on the grinding wheel I6, means are provided for laterally moving the templet holder 32. These means consist of a templet compensating lever 43 with an extending finger 31 adapted to slidably actuate the templet holder 32 within the limits provided by the micro-calibrated stops i] and 5|. 1

The dressing operation is carried out in two steps. First with the templet holder properly positioned against stop 50, edge 39 is centrally positioned with respect to the templet 33, and then moved outwardly in one direction over onehalf of the surface thereof, with diamond 35 engaging the rotating wheel [6.

The compensating lever 43 is then actuated until bracket 32 engages the stop 5|. In this position the edge 39 of bar 31 is again centrally positioned upon the templet 33 and the bar is moved laterally in the opposite direction over the surface of said templet.

Member 29 is longitudinally slidable upon the support 23 within dovetail slot 35 for a very definite purpose. It is seen that by sliding saidsupport that the distance between the templet 33 and the diamond 35 varies with respect to the fixed distance between said diamond and the pivot support as. Thus it will be seen that by longitudinally sliding the support 29 a plurality of different pitches may be obtained from a single templet.

This becomes apparent when it is seen that longitudinal adjustment of the templet varies the proportional movement of the diamond with respect to the grinding wheel, while the movement of the follower bar with respect to the surface of the templet remains substantially the same. Thus as the templet is moved towards the pivotal point 33, it is seen that the diamond movesa greater distance than when the templet is in its initial outermost position. The pitch definedin the grinding edge is thus smaller because the diamond moving further laterally j provides thicker threads and thus less threads to the inch which is the measure of the pitch. I

By a suitable calibration the longitudinal movement of a particular templet to certain predetermined points will result in accomplishing difiere ent predetermined pitches for the particular templet used. By employing the sliding support 29 it will be seen that considerable time is saved whenever it is desired to change the pitch of the thread to be cut by the grinding wheel 16, within the limits of movement of said support. Furthermore, consider-able expense is eliminated by providing one templet which by movement of support 29 permits the dressing of a pluralityof pitches in said grinding wheel.

Follower bar 31 is readily removable from housing H for adjustment or changing of the diamond 35. Referring to Figure 3; the release stud 52 is adjustably threaded within housing II and is adapted to cooperatively engage the pivot dB for retaining the same within said housing. The opposite side of said pivot is engaged by a suitable relatively permanent stud 53. By loosening stud 52, the follower bar 31 may be easily withdrawn from housing H. A locking screw 54 as shown in Figure 5, is employed for retaining said stud 52. i

It is understood that handle 38 may be replaced by a suitable handle bar or other means 1 providing for two-handed manipulation of'bar31.

By the crank action of the trunnion 4 2 pivoted at point 44 on the end of bar 31, the diamond 351s adapted to pivot, thereby causing a different cutting surface of the diamond to be presented to the peripheral edge of the grinding wheel It at each increment of movement of bar 31.

It will be understood that the above dressing mechanism is distinguishable from the pantogr-aph type of dressing mechanism which employs a plurality of links and joints.

The latter type of dresser is subject to Wear at the joints wherein there is a chance for slack and play resulting in a multiplication of the templet error. While in applicants dressing mechanism there is no opportunity for multiplication of such error because there are no links and consequently there is no opportunity for play or slack.

It'is understood that the dressing mechanism above described is also adaptable for surface grinders of various types used in the tool industry for reproducing therein any desired shape.

It will be understood that the bar 31 might operate satisfactorily without the trunnion member 42.

Applicant in Figure 6 illustrates a slightly different form of dressing mechanism wherein the trunnion connection is omitted and in its place a suitable guide is provided for preventing any tilting of the dressing bar.

Referring to Figure 6 the dresser housing II has a slotted opening 55 for receiving the extended shank portion 56 of the ball pivot 45. It will be noted that the central point of extension 56 is directly above the central point of the ball pivot All.

By means of the slotted guide 55 lever 37 cannot tilt laterally about the pivot 45, but it will be seen that said bar 31 may only be translated in vertical and horizontal planes for following the contour of the templet 33. y

In dressing the grinding wheel in making reasonably large included angles between threads as for instance in the neighborhood of forty-five degrees or greater, it is not necessary for the diamond to tilt as itis translated over the peripheral surface of the grinding wheel, because with such an angle or with similar angles, the non-cutting edges of the diam-0nd will not come in contact with the grinding wheel. However in the case of small included angles between the threads the pivoted diamond as set out in Figs. 3 to 5 is more desirable for the reasons above given.

The diamond 35 in this embodiment has a cone shaped point with a flat surface on one face thereof.

A block 51 is disposed on the under side of bar 31 and suitably secured thereto by screws 58.

Said block may be of any desired shape as long as it is similar in cross section to the cross section of the diamond employed.

Applicant preferably arranges the distance between the pivot 40 and the diamond 35, and the distance between the pivot 40 and the templet width of block 51 is ten times the width of the cutting face of diamond 35, whereby the shape of the templet is correctly reproduced on the peripheral edge of the grinding wheel 46 for obtaining a predetermined pitch. However it is seen that the diamond moves one-tenth as far as the bar 37 at the point where block 51 engages the templet. In grinding Whitworth threads the bottom of the diamond 35 is given a radius or curvature of, for instance, three-thousandths of an inch. In order that the templet may be properly reproduced in the surface of the grinding Wheel it is necessary that the bottom templet engaging edge of block 5! also have a radius so that the cross sectional shape thereof continues to correspond to the shape of the diamond.

In applicants preferable embodiment the ratio of one to ten is employed, and therefor the radius in the bottom of the block 51 will be thirty-thousandths of an inch. It will be understood that it might be desirable to employ a diamond with a different radius where a different pitch is required. In which case it becomes necessary to provide a corresponding block 5! with a proportionately corresponding radius. Block 51 is therefore removable and interchangeable with other blocks having different curvatures at their templet engaging surfaces.

It will be understood that the following limitations however must be imposed upon the angular inclination of the block 51. In order that the sides of the diamond do not contact the grinding wheel it is necessary that the included angle of the block be equal to the included angle of the diamond, or even slightly greater so as to provide the necessary clearance of the sides of said diamond and the grinding wheel. Similarly so the included angle of the block should be slightly less than the included angle of the templet.

As above described templet support 29 is longitudinally adjustable upon the table 28 for obtaining a plurality of pitches in the peripheral edge of the grinding wheel with the use of a single templet.

Where this longitudinal adjustment is desired, the block 57 must be extended longitudinally over the length of follower bar 31 upon the under side thereof, as shown by the dotted lines in Figure 6.

However, as the distance between the templet 33 and the pivot 40 is decreased, the width of block 57 is correspondingly decreased in a gradual taper. Thus the ratio between the width of the cutting face of the diamond 35 and the Width of the block 57 is maintained in the same proportion, as the ratio between the distance between the pivot and the diamond and the pivot and the templet.

In other respects the operation of the embodiment shown in Figure 6 is the same as the embodiment illustrated in Figures 3, 4 and 5.

However, it will be understood that as contrasted with the latter, the follower bar 31 shown in Figure 6 will not tilt laterally but is limited to movement only in longitudinal and vertical planes.

Having described my invention reference should now be had to the claims which follow for determining the scope thereof.

I claim:

1. A dressing mechanism for a grinding wheel comprised of a housing adapted to vertical adjustment with respect thereto, a follower bar pivotally supported within said housing, an arm on the end of said bar pivotally and slidably supported within said'housi'ng, offset with respect to the pivotal support of said bar, a diamond carried by said bar adapted to engage said grinding wheel, a templet carried by said housing, and means for translating said follower bar over the surface of said templet for reproducing its shape by said diamond in the peripheral edge of said grinding wheel, the pivotal supports being adapted to permit tilting of said bar only upon lateral translation thereof, whereby said diamond throughout the dressing operation will substantially normally engage the edges of said grinding wheel.

2. A dressing mechanism for a grinding wheel comprised of a housing, a follower bar pivotally supported within said housing, an arm on the end of said bar pivotally supported within said housing offset with respect to the pivotal support of said bar, said arm pivot support being slidably disposed within said housing whereby said bar will tip only when laterally translated, a diamond carried by said bar adapted to engage said grinding wheel, a templet, and means for translating said follower bar over the surface of said templet for reproducing its shape by said diamond in the peripheral edge of said grinding wheel, said arm support thereby maintaining said diamond in a substantially normal position with respect to the edges of the grinding wheel throughout the dressing operation.

3. A dressing mechanism for a grinding wheel comprised of a housing adapted to adjustment with respect thereto, a follower bar pivotally supported adjacent said housing, an arm on the end of said bar pivotally and slidably supported within said housing, offset with respect to the pivotal support of said bar, a diamond carried by said bar adapted to engage said grinding wheel, a templet carried by said housing, laterally movable with respect to said grinding wheel, and means for translating said follower bar over the surface of said templet for reproducin its shape by said diamond in the peripheral edge of said grinding wheel, said arm support thereby maintaining said diamond in a substantially normal position with respect to the edges of the grinding wheel throughout the dressing operation.

4. A dressing mechanism for a grinding wheel comprised of a housing, a follower bar pivotally supported within said housing, an arm on the end of said bar pivotally and slidably supported within said housing, offset with respect to the pivotal support of said bar, a diamond carried by said bar adapted toengage said grinding wheel, a templet carried by said housing, laterally movable with respect to said grinding wheel, oppositely disposed means for adjustably limiting said lateral movement, and means for translating said follower bar over the surface of said templet for reproducing its shape by said diamond in the peripheral edge of said grinding wheel, said arm support thereby maintaining said diamond in a substantially normal position with respect to the edges of the grinding wheel throughout the dressing operation.

5. A dressing mechanism for a grinding wheel comprised of a housing, a follower bar pivotally supported within said housing, and also pivotally and slidably supported on its end offset with respect to said pivotal support, a diamond carried by said bar adapted to engage said wheel, a templet supported by said housing, and means for arcuately translating said follower bar over the surface of said templet whereby the shape thereof is reproduced with the size thereof reduced in the peripheral edge of the grinding wheel by said diamond, the offset two point pivotal supports of said bar thereby provide that the diamond be substantially normal to the surface of the grinding wheel throughout the dressing operation.

6. A dressing mechanism for a grinding wheel comprised of a housing adapted to adjustment with respect thereto, a follower bar pivotally supported adjacentsaid housing, an arm on the end of said bar pivotally and slidably supported within said housing, ofiset with respect to the pivotal support of said bar, a diamond carried by said bar adapted to engage said grinding wheel, a templet carried by said housing, laterally movable with respect to said grinding wheel, means for longitudinally adjusting the templet with respect to said diamond for providing a plurality of pitches, and means for translating said follower bar over the surface of said templet for reproducing its shape by said diamond in the peripheral edge of said grinding wheel, said arm support thereby maintaining said diamond in a substantially normal position with respect to the edges of the grinding wheel throughout the dressing operation.

7. A dressing mechanism for a grinding wheel comprised of a housing, a follower bar pivotally supported thereon, an arm on the end of said bar pivotally and slidably supported on said housing, said pivotal supports being offset with respect to each other, a diamond carried by said bar adapted to engage said grinding wheel, a templet on said housing, and means for translating said follower bar over the surface of said templet for reproducing its shape by said diamond in the peripheral edge of said grinding wheel.

8. A dressing mechanism for a grinding wheel comprised of a housing, a follower bar pivotally supported thereon, an arm on the end of said bar pivotally and slidably supported on said housing, said supports being offset, a diamond carried by said bar adapted to engage said grinding wheel, a templet on said housing laterally movable with respect to said grinding wheel, and means for translating said follower bar over the surface of said templet for reproducing its shape by said diamond in the peripheral edge of said grinding wheel, said arm thereby maintaining said diamond in a substantially normal position with respect to the edges of the grinding wheel throughout the dressing operation.

9. A dressing mechanism for a grinding wheel comprised of a housing, a follower bar pivotally supported thereon, an arm on the end of said bar pivotally and slidably supported on said housing offset with respect to the pivotal support of said bar, a diamond carried by said bar adapted to engage said grinding wheel, a templet on said housing, means for longitudinally adjusting said templet with respect to said grinding wheel, and means for translating said follower bar over the surface of said templet for reproducing its shape by said diamond in the peripheral edge of said grinding wheel, said arm thereby maintaining said diamond in a substantially normal position with respect to the edges of the grinding wheel throughout the dressing operation.

JOHN SNEED. 

